Drive mechanism for sheet turning device in multicolor printing machines



July 15, 1969 o. RUDOLPH ETAL 3,455,547

DRIVE MECHAN FOR SHEET TURNING DEVICE IN MULTI OR PRINTING MACHINESFiled July 12, 1967 3 Sheets-Sheet 1 INVENTORS OTFR RU DOL PH GUNT LUCIUS July 15, 1969 o. RUDOLPH ETAL 3,455,547

DRIVE MECHANISM FOR SHEET TURNING DEVICE IN MULTIGOLOR PRINTING MACHINESFiled July 12, 1967 3 Sheets-Sheet 2 N INVENTORS 5 OIFRIED RUDOLPHGUNTER LUCIUS 3,455,547 T '1 R ING DEVICE IN NG HINES July 15, 1969 o.RUDOLPH ETAL DRIVE MECHAN F HEE MULTI O NTI Filed July 12. 1967 3Sheets-Sheet 5' FIG.

INVENTORS OIFRIED RUDOLPH GUNTER LUCIUS 3,455,547 DRIVE MECHANISM FORSHEET TURNING DE- VICE IN MULTICOLOR PRINTING MACHINES Otfried Rudolph,Dresden, and Giinter Lucius, Boxdorf, Germany, assignors to VEBDruckmaschlnenwerk Planeta, Radebeul, Germany Filed July 12, 1967, Ser.No. 652,753

Int. Cl. B65h 29/06 US. Cl. 27182 6 Claims ABSTRACT OF THE DISCLOSUREDisclosed is a drive mechanism for a pair of sheet turning grippersoperatively arranged on a sheet transfer cylinder. The grippers arecoupled one to another by two gear segments. A profiled cam is fixedlydisposed close to the surface area of the side wall of the transfercylinder. A cam follower rocker is urged by first spring means to followthe circumference of the cam and linked by an intermediate coupling armto one of the grippers to force the coupled grippers into a swing-inposition when the cam follower rocker travels on the lower .profile ofthe cam. A second spring means urges the coupled grippers into aswing-out position when the cam follower travels on the elevated profileof the cam and relieves the tenslon in the coupling arm. Locking meansare provided at one of the gear segments to optionally lock the grippersin their swing-out .position.

The present invention relates to a drive mechanism for a sheet turningdevice in multicolor rotary printing machines with successive printingunits having a sheet transport cylinder therebetween, and being in acooperative relationship one to another.

It is known how to turn a sheet between two successive printing units ina rotary multicolor printing machine for the purpose of printing thereverse side of the sheet.

There are known embodiments wherein two gripper sets which areeccentrically arranged on the sheet transport cylinder are swung towardthe center of the transfer cylinder and toward each other at the pointof sheet transfer in order that the sheet delivery from the first set ofgrippers to the second set might be accomplished. After the sheet hasbeen delivered, both gripper sets are swung to their original positionagain and the turned sheet is delivered to the following cylinder. Eachof these grippers, is fixedly mounted on a swing shaft which ispivotably Supported on the transfer cylinder and mounted eccentricallyand parallel to the axis of the latter. A swing drive which iscorrelated to each set of grippers comprises: A hub pinion gear fixed tothe end of each swing shaft, respectively, the gear teeth of which areengaged with a gear segment. The gear segment is supported on a pivotwhich is mounted on the side disc of the transfer cylinder. The latterpivot supports also a cam follower rocker having a rotary roll followerat its end. This roll follower is, during the rotation of the sheettransfer cylinder, in a slidable contact with a stationary cam disposedfor cooperation with a roll follower. The gear segment iscounterclockwise urged by means of spiral springs which are mounted onthe side disc of the transfer cylinder. An ad justable limit stop isseated on the gear segment to limit the counterclockwise pivoting of thecam follower rocker, the pivotal motion of which results due to theaction of a pressure spring disposed between the gear segment and thecam follower rocker. A limit stop for the hub pinion gear seating on theside disc of the transfer cylinder, limits pivoting of the swing shaftin the clockwise direction. Another adjustable limit stop limits thepivoting of the swing shaft in the counterclockwise direction.

nited States Patent Patented July 15, 1969 Therefore, during the motionof the cam follower rocker in the clockwise direction, the springs movethe gear segment in the clockwise direction against the pressure of thespiral springs and, simultaneously, the gear segment is pivoted in theclockwise direction so that the hub pinion gear pivots counterclockwisethe swing shaft ab out its axis.

If the sets of grippers should not swing during the rotation of thesheet transfer cylinder, which requirement may be, for example, in thecase of printing on the obverse side of the sheet, then as a consequenceof the cinematic structure of the swing drive, it is necessary to removethe cam disposed within the orbit of the roll follower in order thatduring the rotation of the transfer cylinder the roll follower mightcirculate without obstacles on a circular path.

The shortcoming of the aforementioned swing drive is that each of theboth sets of grippers is driven by a sep arate swing drive.

A separate drive for each of the gripper sets represents, however, anexpensive technical design and installation, requiring a considerableamount of material.

Especially in case of large sheet transfer cylinders upon which twosheet turning systems and consequently four sets of grippers arearranged, the installation of separate swing drives for the fourrespective sets of grippers is, owing to the insufficient room on theside disc surface and in axial direction thereof particularlydisadvantageous.

It has been tried to adjust by means of fixed and adjustable limit stopsthe exact position of the gripper sets during seizing of the sheet,during transferring the sheet from the first gripper set to the secondgripper set, and during transferring of the sheet to the grippers of thegripping system on the following cylinder. Due to the effect of thelimit stops and the effect of the pressure springs, a backlash of thegear teeth flanks occurs in the hub pinion gears and consequently asmooth operation of the machine, particularly at increased speeed,cannot be guaranteed, so that the capacity of the printing machine islimited for lower speeds only. If the sets of grippers should not swingduring multicolor first form printing, then the cam, lying inside thecircular path of the follower, has to be removed. Due to the unfavorableroom conditions, the demounting of the cam is very difficult andtime-consuming; when adjusting the cam one has to take care to place thecam exactly to its original position.

The object of this invention is to reduce the technical and operationaldisadvantages for the prior art swing drive of the sheet turningsystems, so that particularly the material consumption and cost ofproduction are reduced.

A further object of this invention is to improve the technical andoperational design of the drive mechanism for sheet turning devices andto increase the efiiciency of the printing machine, in spite ofreduction of the installation expenses.

Still a further object of this invention is to shorten the time neededfor the cam re-adjustment and to simplify the change-over from theobverse side printing adjustment to the adjustment for the printing onthe reverse side of the sheet so that an increase of the productivity ofthe printing machine can be attained.

The purpose of the present invention is to carry out the motionalprocesses of the sheet turning device by means of a single swing driveonly which drive is particularly applicable for a transfer cylinder witha twofold increased diameter. Another purpose of this invention is tocarry out a swing drive having a simple cinematic structure.

In accordance with the present invention, the above objects are attainedso that the known sheet turning systems are linked one to another bymeans of gear seg- 3 ments or by a couple for a guided motion, biased bymeans of springs, and driven by means of a four-bar linkage, preferablyin the form of a double rocker.

The roll follower is so adjusted that the sheet turning systems areswung out when the roll follower is on the respective highest point ofthe curved circumference of the cam. The roll follower is urged againstthe curved cam circumference by a torsion-bar spring.

In order that the present invention may be readily carried into effect,it will now be descibed with reference to the accompanying drawings,wherein:

FIG. 1 shows a schematic view of the swing drives according to thepresent invention, applied for two sheet turning devices of a sheettransfer cylinder between two printing units, whereby the sheet turninggrippers are coupled one to another and positively actuated by means ofgear segments;

FIG. 2 shows schematically a sectional view, taken along line AA of FIG.1, of a swing drive and of suction grippers;

FIG. 3 shows schematically a sectional view, taken along line BB of FIG.1, of a swing drive and of mechanical grippers.

FIG. 4 shows a schematic side view of a swing drive for a sheet turningdevice whereby the sheet turning grippers are linked together forpositive motion by means of a coupling arm; and

FIG. 5 shows schematically the adjustment of the sheet turning device ina locked swungout position.

As shown in FIG. 1, two sheet turning devices are arranged on a sheettransfer cylinder 1 having a twofold diameter with respect tocooperating press cylinders (not shown) whereby the first sheet turningdevice is in a swung-in position, and the second sheet turning device isin a swung-out position. Each two sheet turning grippers 2, 3 and 4, 5respectively, represent a sheet turning device. In this embodiment ofthe invention, the sheet turning grippers 2 and 4, are carried out assuction grippers and, on the other hand, the sheet turning grippers 3and 5 have the form of mechanical grippers.

The sheet turning grippers 2, 3 and 4t, 5 respectively, are fixedlyarranged on pivots 6, 7, 8 and 9, which are suitably journaled in theside wall or disc of the sheet transfer cylinder 1. On each end of thepivots 6, 7, 8 and 9 respectively, gear segments 10, 11, 12 and 13 areafiixed in such a manner that the gear segments pertaining to separatesheet turning devices 2, 3 and 4, 5 are engaged one to another for apositively actuated motion. The device mechanism for swinging out and inthe two pairs of grippers in a predetermined time relationship is inaccordance with the present invention carried out as follows: Camfollower rockers 14 and 15 are pivotably supported on pivots 16 and 17,respectively. The cam follower rockers 14 (and 15) and the gear segments10 (and 12) are pivotably linked, according to one feature of thepresent invention, by means of jointed coupling arms 18 and 19,respectively. The jointed coupling arms 18 and 19 are connected by pinjoints 20 and 21 to the cam follower rockers 14 and 15 and by means ofpin joints 22 and 23 to the gear segments 10 and 12, respectively.

The respective cam follower rockers 14 and 15, coupling arms 18 and 19,and gear segments 10 and 12 owing to the engagement of their teeth,constitute for each gripper in one sheet turning device a four-jointlinkage which thus represents a synchronized double rocker member.

The coupling between the swinging cam follower rockers 14 and 15, andthe sheet turning grippers 2 and 4 is in this manner produced by meansof simply shaped coupling arms 18 and 19 only. Furthermore, since bothsheet turning grippers 2, 3 and 4, 5 are engaged together by gearsegments 10, 11, and 12, 13, so for driving of a. sheet turning deviceonly one four-joint linkage, working as a double rocker, is necesary.

A drive for a sheet turning device can be also carried out, for example,as a four-joint linkage having the form of a crank-guide.

It is also possible to connect positively the sheet turning grippers 2,3 and 4, 5 one to another by means of a coupling rod 43 (FIG. 4). Forthis purpose, the coupling rod 43 links, for example, the swing lever 44which is rigidly mounted on a pivot 6, and swing lever 45 rigidlyconnected to the pivot 7.

To force the geared grippers in one sheet turning device into aswing-out position, pushing springs 32 and 33 bias each pair of grippersinto the radial direction. The springs 32 and 33 are disposed onsupporting rods 26 and 27 which at one end are hinged to respectivelevers 24 and 25 aflixed on pivots 7 and 9. The opposite end portions ofrods 26 and 27 are slidably guided in guide members 30 and 31 rigidlyconnected to the side wall of the transfer cylinder 1: Springs 32, 33span the entire drive in any position of the sheet turning devices 2, 3and 3, 4 so that the backlash of the entire swing drive, caused by theproduction inaccuracy, is neutralized by means of forces which actalways in the same direction. The teeth backlash canot consequentlyoccur. If the pivots 7,9 are produced, for example, as hollow shafts,then the springs 32, 33 can be substituted by torsion bar springsdisposed within the corresponding hollow shaft.

Roll followers 34, 35 are pivotably supported in the cam followerrockers 14, 15, respectively (FIGS. 1 and 2). The roll followers 34, 35travel during the rotation of the sheet transfer cylinder 1, on thecurved circumference 36 of cam 38 fixedly mounted to the frame wall 37of the printing machine, so that the swinging movement cam followerrockers 14, 15 and consequently, the positions of the sheet turningdevices 2, 3 and 4, 5 are controlled in dependence on the shape of thecam circumference 36. The jointed coupling arms 18 and 19 are mounted onthe cam follower rockers 14, 15 in such a manner that the sheet turningdevices 2, 3 and 4, 5 are, due to the action of springs 32 and 33, in aswung-out position when the roll followers 34, 35 are travelling overthe elevated area of the curved circumference 36. In case of printing,on the obverse side of the sheets, the sheet turning grippers 3, 5 arearrested in the swung-out position by means of screw 39 (FIG. 5). Thescrew 39 firmly connects the sheet turning devices 3 and 5 with a rail40 which is fixedly mounted in the sheet transfer cylinder 1. In such asimple manner, only by fixing a locking member into a positively coupledswing drive, the swing motion of the sheet turning systems 2, 3 and 4, 5is made inoperative. For this reason, it is not necessary to demount thecam or other drive members for blocking the swing motion of the sheetturning devices 2, 3 and 4, 5. The slidable contact of the roll follower34 with the cam circumference 36 is safeguarded by means of atorsion-bar spring 41. The torsion-bar spring 41 is at one end fixed tothe cam follower rocker 14 and at the other end to a spring collet 42.The effects of the torsion-bar spring 41 and of the spring 33 aresupplementary one to another. The roll follower 35 is forced against thecam circumference 36 in the same manner as the roll follower 34.

The turning of sheets is carried out in conventional manner at thepoints of contact between the cylinders of cooperating printing units(not shown) and the transfer cylinder 1. The trailing edge of the sheetto be turned over is grasped at a contact point by means of suctiongripper 2, for example, which in FIG. 1 is shown in a swing-outposition, i.e., in alignment with the radius of the side wall of thetransfer cylinder 1.

At the moment when the suction gripper 2 has grasped thetrailing edge ofthe sheet, the leading edge of the latter is released from grippers onthe impression cylinder and the sheet is carried in counterclockwisedirection by the transfer cylinder 1. As soon as the cam follower rocker14 enters the lowered section on the cam circumference, the gearedgrippers 2 and 3 are forced, due to the action of the spring 41 and ofthe jointed coupling arm 18, into the swing-in position. In the latterposition the sheet is released from the suction gripper 2 and grasped bythe mechanical gripper 3. Subsequently, the rocker 14 enters theelevated section of the cam circumference, the grippers swing open andthe turning of the sheet is accomplished. During the further rotation ofthe transfer cylinder, the reversed sheet is delivered in a known mannerto the adjacent cylinder of the following printing unit.

What is claimed is:

1. In a multicolor rotary printing machine having successive printingunits with a sheet transfer cylinder therebetween, at least a sheetturning device operatively disposed on the transfer cylinder and havinga first and second gripper means supported on pivots respectivelyjournalled in the side wall of said transfer cylinder, a drive mechanismfor said sheet turning device, comprising: gripper coupling means forpositively imparting the motion of said first gripper to said secondgripper, profiled cam means fixedly disposed close to central area ofsaid side wall, cam follower rocker means journalled at one end to saidside wall, first spring means for urging said cam follower rocker meansagainst the profiled circumference of said cam means, the opposite endof said cam follower rocker being coupled to the first one of saidgrippers by means of a jointed coupling arm for forcing said grippersinto a swing-in position when said cam follower rocker travels in thelowered profile section of said cam means, and second spring meanscoupled to the second one of said grippers to force said grippers into aswingout position during the travel of the cam follower rocker in theelevated section of said cam means.

2. In the printing machine according to claim 1 wherein said grippercoupling means comprises two gear segments respectively fixed to saidpivots and being in engagement one to another for a positively actuatedmotion.

3. In the printing machine according to claim 1 wherein said couplingmeans comprise a first lever affixed to the pivot of said first gripper,a second lever affixed to the pivot of said second gripper, and acoupling rod hinged between said first lever and said second lever toprovide a double rocker four-joint linkage.

4. In the printing machine according to claim 1 wherein said secondspring means comprise a torsion bar spring arranged coaxially within thehollow pivot of said second gripper. Y

5. In the printing machine according to claim 1 wherein said camfollower rocker is urged against said cam circumference by means of atension bar spring mounted parallel to the axis of said transfercylinder.

6. In the printing machine according to claim 1, lock means comprising arail fixedly mounted to the sheet transfer cylinder for arresting thesheet turning device in the swing-out position by means of a screw.

References Cited UNITED STATES PATENTS 2,757,610 8/1956 Gegenheimer101-183 EDWARD A. SROKA, Primary Examiner

